Mask Manufacturing Device

ABSTRACT

According to one embodiment, a mask manufacturing method includes acquiring positional deviation information between an actual position of a pattern formed on a mask substrate and a design position decided at the time of designing the pattern; calculating an irradiating amount and an irradiating position of radiation to be irradiated to a predetermined area of a square on the mask substrate according to the calculated positional deviation information; and irradiating the radiation based on the calculated irradiating amount and the calculated irradiating position to form in a part of the mask substrate a heterogeneous layer of which volume is expanded more greatly than that of the surrounding mask substrate region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 13/326,612,filed on Dec. 15, 2011, which is a divisional of U.S. patent applicationSer. No. 12/350,394, filed on Jan. 8, 2009, which issued as U.S. Pat.No. 8,097,539 on Jan. 17, 2012, and claims priority to Japanese patentapplication No. 2008-3504, filed on Jan. 10, 2008; each incorporatedherein by reference for all purposes.

BACKGROUND

1. Field

Embodiments described herein relate to a mask manufacturing method, anda semiconductor device manufacturing method.

2. Description of the Related Art

Recently, along with advancement of downsizing of semiconductor devices,a problem in a photolithography step in the semiconductor devicemanufacturing process has become remarkable. Concretely, in a designrule of the latest semiconductor device at this point, downsizing has soadvanced that the half pitch (hp) is about 22 nanometers, and when theconventional lithography by a reduced pattern transcription using lightis used, resolution of this order cannot be achieved, resulting in asituation where the pattern formation has become difficult. As a result,in recent years, instead of the lithography, nanoimprint technique hasbeen employed.

The nanoimprinting is a technique for forming a pattern on a substrate.Concretely, the nanoimprinting includes pressing an imprint mask havinga pattern shape formed thereon against an imprint material (a coatingmaterial) coated on the substrate, waiting until the imprint materialsolidifies thereby forming a model of the pattern shape on the imprintmask. The nanoimprinting is free of variable factors such as a focaldepth, aberration, and an exposure amount that caused problem in theconventional lithography that employed light. Moreover, if only a highlyaccurate imprint mask is formed, it is possible to very easily andaccurately transcript the pattern of the imprint mask.

Meanwhile, when manufacturing semiconductor devices, a new pattern issometimes formed on a substrate having an old pattern previously formedthereon. When the nanoimprint technique is used to form such a newpattern, high alignment accuracy is required between the imprint maskand the substrate. A pattern on the imprint mask generally haspositional distortion, so that when forming a new pattern that matcheswith an underlying old pattern, it is preferable to first solve theissue of pattern positional distortion of the imprint mask. With respectto a first-order component deviation such as a magnification, forexample, out of the pattern positional distortion, the deviation can betaken care of by pressing an end surface of the imprint mask. Such atechnique has been disclosed, for example, in D. L. White and O. R. WoodII, “Novel alignment system for imprint lithography”, The Journal ofVacuum Society Technology B 18(6), November/December 2000, AmericanVacuum Society. However, when the imprint mask has a pattern positionaldeviation of a second or higher order complicated shape, or when themagnification needs to be enlarged, for example, there is a problem thatwith the method described in the above-mentioned literature, it is notpossible to solve the pattern positional distortion of the imprint mask.

SUMMARY OF THE INVENTION

According to one embodiment, a mask manufacturing method includesacquiring positional deviation information between an actual position ofa pattern formed on a mask substrate and a design position decided atthe time of designing the pattern; calculating an irradiating amount andan irradiating position of radiation to be irradiated to a predeterminedarea of a square on the mask substrate according to the calculatedpositional deviation information; and irradiating the radiation based onthe calculated irradiating amount and the calculated irradiatingposition to form in a part of the mask substrate a heterogeneous layerof which volume is expanded more greatly than that of the surroundingmask substrate region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of one example of a functionalconfiguration of an imprint mask manufacturing device according to anembodiment of the present invention;

FIGS. 2A and 2B are schematic diagrams of a reference pattern formed onan imprint mask substrate;

FIG. 3 is a graph of one example of positional-deviation correctioninformation;

FIG. 4 is a flowchart of one example of a procedure of an imprint maskmanufacturing method executed by the imprint mask manufacturing deviceshown in FIG. 1;

FIG. 5 is a schematic plan view of a situation where positionaldeviation of the imprint mask has occurred;

FIG. 6 is a schematic cross-sectional view of a situation wherepositional deviation of a pattern position has occurred after formationof the imprint mask;

FIG. 7 is a schematic cross-sectional view of a situation where laser isbeing irradiated to the imprint mask;

FIGS. 8A and 8B are schematic partial plan views of situations where thepattern position has been corrected by way of laser irradiation to theimprint mask shown in FIG. 5; and

FIGS. 9A and 9B are schematic cross-sectional views of imprint maskshaving different shapes due to differing positions of formationpositions of a heterogeneous layer.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments of an imprint mask manufacturing method, an imprint maskmanufacturing device, and a semiconductor device manufacturing methodaccording to the present invention will be explained below in detailwith reference to the accompanying drawings. The present invention isnot limited to the following embodiments. Cross-sectional views of animprint mask in the following embodiment are only schematic, and do notrepresent the actual ratio.

FIG. 1 is a schematic block diagram of one example of a functionalconfiguration of an imprint mask manufacturing device 10 according to anembodiment of the present invention. The imprint mask manufacturingdevice 10 includes a positional-deviation detector 11, apositional-deviation correction-information storage unit 12, alaser-irradiation-condition calculating unit 13, apositional-deviation-information storage unit 14, a laser irradiatingunit 15, and a controller 16 that controls each of the processing units.

The positional-deviation detector 11 detects a positional deviation of apredetermined position on the mask substrate from an ideal position of areference pattern actually formed on a mask substrate, and thencalculates a pattern-position change rate indicating a ratio of thepositional deviation to a distance between adjacent ideal referencepatterns. In the present embodiment, the predetermined position on themask substrate is assumed to be a positional-deviation corrected regionsurrounded by reference patterns formed on the mask substrate. Thepattern-position change rate calculated by the positional-deviationdetector 11 is associated with the positional-deviation correctedregion, and stored in the positional-deviation-information storage unit14. The reference pattern is prepared for detecting a positionaldeviation (positional distortion) of the pattern for manufacturing asemiconductor device formed on the mask substrate, and on the design,determined to be formed at a predetermined interval. The positionaldeviation can be detected with a laser interferometer or the like.

FIG. 2A and FIG. 2B are schematic diagrams of a reference pattern formedon an imprint mask substrate. Particularly, FIG. 2A is a schematic planview of one example of a relationship between actual positions ofreference patterns formed on an imprint mask substrate and idealpositions, and FIG. 2B is for explaining one example of a method ofcalculation of a positional deviation amount of the reference pattern.In FIGS. 2A and 2B, cross patterns 31, drawn with a solid line, indicatethe actual positions at which the reference patterns are formed on amask substrate 30 (hereinafter, also “substrate 30”) and circularpatterns 32, drawn with a dotted line, indicate the ideal positions onthe mask substrate 30 at which the reference patterns are placed. Eachideal position of the reference pattern is a designed reference-patternposition, for example. Two directions orthogonal to each other on themask substrate 30 are an x-axis direction and a y-axis direction.

As indicated by each circular pattern 32 in FIG. 2A, it is desired thatthe reference patterns are formed in a lattice at a predeterminedinterval (for example, 5-mm interval) in both the x-axis direction andthe y-axis direction on the mask substrate 30. However, in practice, asindicated by each cross pattern 31, the actual positions of thereference patterns are can deviate from the ideal positions (thecircular patterns 32). In this case, with respect to the smallestrectangular region (the positional-deviation corrected region)configured by the four reference patterns out of a plurality ofreference patterns formed on the mask substrate 30, thepositional-deviation detector 11 detects a positional deviation amountfrom the ideal position (the circular pattern 32) by using the actualpositions (the cross patterns 31) of the reference patterns adjacentwith respect to each of the x-axis direction and the y-axis direction.The positional-deviation detector 11 calculates the pattern-positionchange rate, which is a ratio of the positional deviation amount of eachof the x-axis direction and the y-axis direction with respect to adistance between the ideal reference patterns (the circular patterns32). The pattern-position change rates are calculated for all thepositional-deviation corrected regions.

A case of evaluating the pattern-position change rate in apositional-deviation corrected region R surrounded by cross patterns31-1 to 31-4 by four solid lines shown in FIG. 2B has been described asan example. A pattern-position change rate of the positional-deviationcorrected region R in the x-axis direction is to be calculated by usinga detection result on the top side of the positional-deviation correctedregion R, and a pattern-position change rate in the y-axis direction isto be calculated by using a detection result of the right side of thepositional-deviation corrected region R.

A positional deviation amount Δx of the positional-deviation correctedregion R in the x-axis direction is calculated, based on theprecondition, as a difference between a distance x_(r) in the x-axisdirection between the cross patterns 31-1 and 31-2 configuring the topside of the positional-deviation corrected region R, and a distancex_(i) in the x-axis direction between the circular patterns 32 oradjacent reference patterns formed at the ideal positions. A positionaldeviation amount Δy of the positional-deviation corrected region R inthe y-axis direction is similarly calculated as a difference between adistance y_(r) in the y-axis direction between the cross patterns 31-2and 31-4 configuring the right side of the positional-deviationcorrected region R, and a distance y_(i) in the y-axis direction betweenthe adjacent circular patterns 32 formed at the corresponding idealpositions.

The pattern-position change rate in the x-axis direction is thenevaluated according to Δx/x_(i), where Δx denotes a positional deviationamount in the x-axis direction for the distance x_(i) between thereference patterns (the circular patterns 32) at the ideal positions.The pattern-position change rate in the y-axis direction is similarlyevaluated according to Δy/y_(i), where Δy denotes a positional deviationamount in the y-axis direction for the distance y_(i) between thereference patterns (the circular patterns 32) at the ideal positions.The positional deviation amounts Δx and Δy are expressed by an absolutevalue of a deviation from the ideal position. The pattern-positionchange rates are evaluated as a macro positional deviation amount in theorder of millimeter, obtained by accumulating positional deviations innanometer order.

In the above example, for the detection of the pattern positionaldeviation on the mask substrate, a case that the reference patternsformed on the mask substrate are used is described. However, instead offorming the reference patterns on the mask substrate, it is possible todetect a positional deviation of a mask pattern, formed on the masksubstrate, for forming a device pattern of a normal semiconductordevice. That is, a positional deviation from an ideal position of thedevice pattern forming pattern formed on the mask substrate can bedetected.

The positional-deviation correction-information storage unit 12 storestherein positional-deviation correction information indicating arelationship between a laser irradiating amount and a laser irradiatingposition for the mask substrate, and a pattern-position change amount(rate) after the laser irradiation. The positional-deviation correctioninformation differs depending on a difference in wavelength of a laserbeam to be irradiated, the output thereof, the beam radius thereof, thebeam length thereof, a mask-substrate material or the like, and thus itis previously evaluated by an experiment. In the present embodiment, asthe laser irradiating amount, the number of laser pulses to beirradiated is used.

FIG. 3 is a graph of one example of positional-deviation correctioninformation indicating a relationship between a laser irradiating amountand a pattern position change amount (rate) when the irradiatingposition is near the center of the thickness of the mask substrate. InFIG. 3, the horizontal axis indicates the number of laser pulses to beirradiated (hereinafter, “laser-pulse irradiating density”) per unitarea, and the vertical axis indicates a pattern-position change rate inan expanding direction. The positional-deviation correction informationis evaluated as a ratio of a positional change on a side of a squarewhen a predetermined area (for example, an area of 10 squaremillimeters) of a square near the center in the thickness direction of amask substrate is irradiated with a predetermined number of laserpulses. As shown in FIG. 3, there is a high correlation between thelaser-pulse irradiating density and the pattern-position change rate,and the lower the laser-pulse irradiating density, the smaller thepattern-position change rate, and the higher the laser-pulse irradiatingdensity, the larger the pattern-position change rate. That is, when adeviation amount from the ideal pattern position of the actual patternposition is known, the laser-pulse irradiating density for correctingthe deviation amount can be evaluated from the positional-deviationcorrection information.

This example provides a case that as the positional-deviation correctioninformation, the relationship between the laser-pulse irradiatingdensity and the ratio of the positional change when the irradiatingposition is near the center of the thickness of the mask substrate isused. In addition, thereto, a relationship between an irradiatingposition in the thickness direction of the mask substrate and apositional change amount (ratio) can be used. The positional-deviationcorrection information in this case is evaluated as a positional changeamount (ratio) on a side of a square when each position in the thicknessdirection of a predetermined area (an area of 10 square millimeters, forexample) of a square of the mask substrate, for example, is irradiatedwith a predetermined amount of laser pulses. In addition, thereto, arelationship between the irradiating position in the thickness directionof the mask substrate and the positional change amount (rate), or arelationship between the irradiating position in a horizontal directionof the mask substrate and the positional change amount (rate) can beused to evaluate the positional-deviation correction information.

From the pattern-position change amount (rate) of thepositional-deviation corrected region R, the laser-irradiation-conditioncalculating unit 13 uses the positional-deviation correction informationto evaluate a laser-pulse irradiating condition, e.g., the laser-pulseirradiating density, for solving the positional deviation, andmultiplies the laser-pulse irradiating density by an area of eachpositional-deviation corrected region R, thereby calculating the numberof laser pulses to be irradiated in each positional-deviation correctedregion R. The laser irradiating condition calculated in this caseincludes irradiating conditions such as the laser irradiating amount andthe laser irradiating position. The irradiating conditions such as thenumber of laser pulses to be irradiated are stored in thepositional-deviation-information storage unit 14 while being associatedwith each positional-deviation corrected region. In this case, anexample in which the irradiating position of the laser pulse is fixed tonear the center in the thickness direction of the mask substrate isused, and thus an example in which the laser-irradiation-conditioncalculating unit 13 uses the positional-deviation correction informationto calculate the laser irradiating amount is shown. However, the laserirradiating position when the irradiating amount of the laser pulse isfixed to a predetermined value can be calculated, for example.

When the pattern-position change rate differs in the x-axis directionand the y-axis direction in the positional-deviation corrected region R,a pattern-position change rate of which the value is negative (valuethat represents a change in a direction into which a distance betweenthe adjacent patterns is reduced) and also a value of which the absolutevalue is larger is used to calculate the laser irradiating amount.Further, when the pattern-position change rate indicates a value of anexpanded direction, the positional deviation correction by the laserirradiation is not performed. The reason for this is that the correctionof the positional deviation by the laser irradiation utilizes a volumeexpansion of the mask substrate to correct the pattern formed byconstriction, and therefore it is not possible to correct the patternformed by expansion in a constricting manner. When the pattern-positionchange rate is equal to or less than 0, the positional-deviationcorrection is not performed on the positional-deviation correctedregion, and thus, by the calculation of the laser irradiating amount, aregion in which the positional-deviation correction is performed is set.

The positional-deviation-information storage unit 14 stores, as thepositional-deviation information, the pattern-position change amount(rate) detected by the positional-deviation detector 11 and the laserirradiating condition of each positional-deviation corrected region onthe substrate calculated by the laser-irradiation-condition calculatingunit 13 in a manner to associate the rate and condition with thepositional-deviation corrected region on the mask substrate. Thepattern-position change rate stored in thepositional-deviation-information storage unit 14 needs to be apattern-position change rate of a device-pattern forming mask patternformed on the mask substrate. However, as shown in this example, it canbe a pattern-position change rate calculated by using the referencepattern instead of the device-pattern forming mask pattern. Further, thelaser irradiating condition in the positional-deviation informationincludes an irradiating position or position of a mask substrate withwhich the laser is irradiated, and an irradiating amount of the laserirradiated in that position. The irradiating position is stored in thepositional-deviation-information storage unit 14, for example, aposition deviated by a predetermined distance in the thickness directionof the mask substrate or the horizontal direction thereof from thecenter of the device pattern.

The laser irradiating unit 15 irradiates each position(positional-deviation corrected region) on the mask substrate with alaser beam of a predetermined number of pulses, based on the laserirradiating condition in each positional-deviation corrected regionstored in the positional-deviation-information storage unit 14. Thelaser irradiating unit 15 includes a substrate holding function ofholding the mask substrate, a laser light source that irradiates thesubstrate with a laser beam, a positioning function for irradiating aposition on the mask substrate included in the positional deviationinformation with a laser beam. For the laser light source, an infraredlaser light source that outputs an infrared laser such as a YAG (YttriumAluminum Garnet) laser and a carbon dioxide gas laser in a pulse shapeis used. The laser light source is configured to set so that the laserlight is focused on a predetermined position (for example, near thecenter) in the thickness direction of the substrate.

By the imprint mask manufacturing device thus configured, a portion of apredetermined depth (in this case, near the center of the thicknessdirection) from the surface of the mask substrate of each position (forexample, a position defined by an orthogonal coordinate system where thecenter of the device-pattern forming mask pattern is the origin) atwhich the correction of the mask substrate is performed, is irradiatedwith a laser beam of the number of laser pulses to be irradiatedaccording to the pattern-position change rate at that position. At theposition with which the laser light is irradiated, a temperature risesinstantaneously, and melted for a very short period of time, andthereafter, immediately cooled. Therefore, a heterogeneous layerincreased in volume slightly more than the surrounding areas is formed.In the heterogeneous layer, the volume becomes greater than that of thesurrounding mask substrate region, and thus each pattern is displaced inan expanding manner. As a result, the actual position is brought closeto the ideal pattern position. In this way, even in the imprint maskthat ends up with having a complicated positional distortion of a secondor higher order, it becomes possible to bring the pattern position closeto the ideal pattern position.

Subsequently, an imprint mask manufacturing method is described. FIG. 4is a flowchart of one example of a procedure of the imprint maskmanufacturing method executed by the imprint mask manufacturing device10. Firstly, a resist layer is formed on the entire surface of a masksubstrate such as a quartz substrate, and a resist pattern (for example,a gate layer pattern for forming a gate layer of a memory device in hp22 nanometers) is formed in a predetermined dimension and in apredetermined shape by an exposure process and a development process inwhich an electron beam or an X-ray is irradiated. In this example, thepatterns to be formed on the mask substrate include a reference patternfor detecting the positional deviation of the pattern on the masksubstrate, and thus the patterns in a lattice as shown in FIG. 2 are tobe formed. However, the reference pattern is not always necessary, and adevice pattern forming pattern formed on the mask substrate can be usedinstead thereof. The resist pattern is used as a mask to etch the masksubstrate, and thereafter, the resist pattern is removed to form thepattern on the mask substrate (Step S11). The mask substrate formedthereon with the pattern is also called an imprint mask below. In thisexample, a quartz substrate of about 6 millimeters in thickness isprocessed to form the imprint mask.

Normally, at the time of the pattern formation on the mask substrate,due to influence of a stress caused by the resist (other than theresist, a film used as a mask is sometimes formed) formed on the masksubstrate or a limitation of drawing accuracy of a drawing device in anexposure process, the positional deviation (positional distortion) inwhich the position of the formed pattern is deviated from the idealposition occurs.

FIG. 5 is a schematic plan view of a situation where positionaldeviation of the imprint mask has occurred. In FIG. 5, a state of oneportion of the surface of the imprint mask on the pattern formed side isshown. Dotted lines indicate ideal pattern positions 41, and solid linesindicate actually formed pattern positions 42. In this example, half aninterval of the ideal pattern positions 41 is about 20 nanometers.However, the pattern positions 41 and 42 do not indicate the actualpattern widths, but indicate a center position of the pattern. In FIG.5, one portion of the patterns within the imprint mask is shown, and anexample of the entire positional deviation of the imprint mask is shownin FIG. 2.

As shown in FIG. 5, the actual pattern positions 42 formed on the masksubstrate by etching have a complicated shape of second or higher order.At locations near a center portion 43 and at four corners 44 of thepattern position, the actual pattern positions 42 are substantiallycoincident with the ideal pattern positions 41. However, near centerportions 45 on each side of the pattern position, the positionaldeviation is generated in a manner to be close to around the centerportion 43.

Subsequently, by the positional-deviation detector 11, the positionaldeviation from the ideal position of the pattern formed on the masksubstrate in a lattice is measured to calculate the pattern-positionchange rate indicating a deviation degree of the actual pattern positionfrom the ideal pattern position in each position on the mask substrate(Step S12). For example, the measurement of the pattern-position changerate is evaluated for each positional-deviation corrected region R in asquare shape surrounded by the four patterns, as shown in FIG. 2. Theevaluated pattern-position change rate is stored in thepositional-deviation-information storage unit 14 while being associatedwith the positional-deviation corrected region R.

FIG. 6 is a schematic cross-sectional view of a situation wherepositional deviation of a pattern position has occurred after formationof the imprint mask. As shown in FIG. 6, it is provided that thepattern-position change rates of four regions, i.e., R_(A), R_(B),R_(C), and R_(D), present on a certain cross section of the masksubstrate 30 are A, B, 0, and D (A, B, and D are positive integers, andA>B>D is established), respectively. The pattern-position change ratesA, B, 0, and D are stored in the positional-deviation-informationstorage unit 14 as the positional deviation information while beingassociated with each region R_(A), R_(B), R_(C), and R_(D). Thepattern-position change rate evaluated here is calculated on conditionthat a direction into which a distance between the actual referencepatterns is shrunk more greatly than a distance between the idealreference patterns is positive.

Thereafter, the laser-irradiation-condition calculating unit 13 obtainslaser-pulse-irradiating-density information and irradiating positioninformation in the positional-deviation corrected region from a patternchange amount of each positional-deviation corrected region on the masksubstrate based on the positional-deviation correction informationstored in the positional-deviation correction-information storage unit12. For example, the area of the positional-deviation corrected regionis multiplied by the obtained laser-pulse irradiating density tocalculate the number of laser pulses irradiated in thepositional-deviation corrected region (Step S13).

For example, when the pattern-position change rates A, B, 0, and D ofthe regions R_(A), R_(B), R_(C), and R_(D) in FIG. 6 are used, thelaser-pulse irradiating densities can be evaluated as a, b, 0, and d(a>b>d>0) from FIG. 3, respectively. Thereafter, the laser irradiatingdensities are multiplied by the area of the positional-deviationcorrected region. When it is assumed that the area of eachpositional-deviation corrected region is the same, the larger thepattern-position change rate, the greater the number of laser pulses tobe irradiated in the positional-deviation corrected region is set, andthe smaller the pattern-position change rate, the fewer the number oflaser pulses to be irradiated in the positional-deviation correctedregion is set.

The laser irradiating unit 15 irradiates each positional-deviationcorrected region on the substrate with the laser pulse based on thenumber of laser pulses to be irradiated calculated by thelaser-irradiation-condition calculating unit 13 to form a heterogeneouslayer of which the volume is increased more as compared to thesurrounding mask substrate constituent material at a location near thecenter of the thickness direction of the imprint mask (mask substrate)(Step S14).

FIG. 7 is a schematic cross-sectional view of a situation where laser isbeing irradiated to the imprint mask, and FIG. 8 is a schematic partialplan view of situations where the pattern position has been corrected byway of laser irradiation to the imprint mask shown in FIG. 5. FIG. 7corresponds to the cross-sectional view of the imprint mask in FIG. 6,in which the numbers of lasers to be irradiated n_(A), n_(B), n_(C), andn_(D) irradiated in each region R_(A), R_(B), R_(C), and R_(D) areproportional to a, b, 0, and d evaluated at Step S13. When the regionsR_(A), R_(B), and R_(D) each having a pattern positional distortion areirradiated with a laser L, a heterogeneous layer 35 of which the volumeis expanded more greatly than the surrounding areas is thus formed nearthe center of the thickness direction of the mask substrate 30.

FIG. 8A is a schematic partial plan view of a state of the laserirradiation to the imprint mask shown in FIG. 5, and FIG. 8B is aschematic partial plan view of a state of a pattern position changeafter the laser irradiation. When the region having a pattern positionaldistortion as shown in FIG. 5 is irradiated with the laser L, theheterogeneous layer is formed, as described above, and influence of thevolume expansion of the heterogeneous layer is transmittedconcentrically about the center or irradiating position of the laser L,and patterns surrounding the irradiating position of the laser L aredisplaced toward a direction apart from the irradiating position of thelaser L. As a result, as shown in FIG. 8B, in a pattern positiondeviated to a direction into which the distance between the adjacentpatterns occurred at the time of forming the pattern of the imprint maskis reduced, the distance is enlarged. Thereby, the positional deviationof the pattern is solved. The number of laser pulses irradiated in eachpositional-deviation corrected region is set to that required forcorrecting the positional deviation amount. Therefore, because of thelaser irradiation, a displacing amount by which the actual patternposition is close to near the ideal pattern position is achieved.Thereby, the complicated positional distortion in which the patternposition is displaced within 2-dimensional plane is solved, leaving onlythe positional distortion by a first-order magnification component.Besides, in the first-order magnification component, the actual patternposition 42 of the imprint mask is enlarged more greatly as compared tothe ideal pattern position 41, and thus the positional distortion can besolved by simultaneously depressing an end surface of the imprintingmask by the nanoimprint device in a direction of an arrow 50 in FIG. 8B.Accordingly, the manufacturing process of the imprint mask is ended.

Immediately after the pattern formation of the imprint mask (immediatelyafter the etching of the pattern), an amount of the positionaldistortion (positional deviation) of the pattern of a maximum of about 6nanometers was present. However, the imprint mask was manufacturedaccording to the steps described above, and when the residual positionaldistortion that was obtained by removing the first-order magnificationcomponent was examined, it showed a value of about 1 nanometer, whichwas very preferable.

Subsequently, a semiconductor device manufacturing method in which suchan imprint mask is used is described. In this case, a case that theimprint mask is used to form on a processing target film a pattern in aregion in which the resolution is insufficient with photolithography(for example, producing of a memory device), is described.

The entire surface on the processing target film formed on thesemiconductor substrate on which the semiconductor device ismanufactured is coated with a coating material, and the imprint mask andthe substrate are brought into close contact by placing the patternformed surface of the imprint mask manufactured at the manufacturingstep in a manner to face the coating material. Subsequently, positioningbetween the imprint mask and the semiconductor substrate is performed,and thereafter, the imprint mask is pressed against the substrate viathe coating material to deform the coating material, which is cured byheat or light. Thereby, the pattern of the imprint mask is transcribedto the coating material. After the coating material is sufficientlycured, the imprint mask is kept apart from the substrate and theremaining coating material is etched, thereby forming a coating materialpattern on the processing target film on the substrate. The coatingmaterial pattern is used as a mask to perform etching, and thereby, theprocessing target film is processed. As a result, a semiconductor devicehaving desired size and shape can be manufactured.

When the memory device is manufactured by using the imprint mask made inthis manner, alignment accuracy is significantly improved as compared tothe conventional imprint mask, and manufacturing yield of the memorydevice is also significantly improved.

While the case that the substrate is irradiated with an infrared laserto form the heterogeneous layer is described above, the substrate can beirradiated and implanted with a beam of ions such as gallium ions. Inthis case, an ion implantation amount is changed according to thepattern-position change rate. With the ion implantation, similar to thecase of the laser irradiation, it is possible to resolve the positionaldistortion of the pattern of the imprint mask. In this specification,the laser beam or ion beam employed for the formation of theheterogeneous layer is called radiation.

In the above explanations, the laser irradiating position is set to nearthe center of the thickness direction of the substrate. The reason forthis is that when locations near the center of the thickness directionof the substrate are irradiated with a laser, warping of the substrateafter the laser irradiation can be suppressed. However, when it isintentionally desired to impart the warping to the imprint mask afterthe laser irradiation, the heterogeneous layer can be formed not onlynear the center of the thickness direction of the substrate but alsonear a surface on the pattern formed side or near the surface oppositeto the pattern formed side. FIG. 9A and FIG. 9B are schematiccross-sectional views of a change in shape of an imprint mask differeddepending on a formed position of the heterogeneous layer, where FIG. 9Adepicts a case that the heterogeneous layer is formed near the surfaceon the pattern formed side and FIG. 9B depicts a case that theheterogeneous layer is formed near the surface opposite to the patternformed side. When the heterogeneous layer 35 is formed near the surfaceon the pattern formed side of the mask substrate 30 as in FIG. 9A,locations near the surface on the pattern formed side are expanded, andthus the surface on the pattern formed side is widened to perform thecorrection in a manner that the pattern is enlarged. When theheterogeneous layer 35 is formed near the surface opposite to thepattern formed side of the mask substrate 30 as in FIG. 9B, the surfaceopposite to the pattern formed side is widened, and thus the correctionis performed in a manner that the pattern is downsized.

Therefore, according to the above embodiment, the pattern positionaldeviation of the imprint mask can be corrected. More specifically, afterthe formation of the pattern of the imprint mask, the heterogeneouslayer is formed by irradiating a laser based on the position change rateof the pattern, and the positional change of the pattern is occurred byexpansion of the heterogeneous layer. Thus, the positional deviation ofa complicated pattern of second or higher order occurred at the time offorming the pattern of the imprint mask can be eliminated, and theactual pattern position can be corrected to be an ideal position.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A mask manufacturing method comprising: acquiringpositional deviation information between an actual position of a patternformed on a mask substrate and a design position decided at the time ofdesigning the pattern; calculating an irradiating amount and anirradiating position of radiation to be irradiated to a predeterminedarea of a square on the mask substrate according to the calculatedpositional deviation information; and irradiating the radiation based onthe calculated irradiating amount and the calculated irradiatingposition to form in a part of the mask substrate a heterogeneous layerof which volume is expanded more greatly than that of the surroundingmask substrate region.
 2. The mask manufacturing method according toclaim 1, wherein the calculating an irradiating amount of radiationincludes calculating the irradiating amount of the radiation accordingto positional-deviation correction information indicating a relationshipbetween an irradiating amount of the radiation when an irradiatingposition of the radiation in a thickness direction of the mask substrateis fixed and a pattern position change after irradiation of theradiation.
 3. The mask manufacturing method according to claim 2,wherein the irradiating position of the radiation is near a center inthe thickness direction of the mask substrate.
 4. The mask manufacturingmethod according to claim 2, wherein the irradiating position of theradiation is nearer to a front surface in the thickness direction of themask substrate than the center.
 5. The mask manufacturing methodaccording to claim 2, wherein the irradiating position of the radiationis nearer to a back surface in the thickness direction of the masksubstrate than the center.
 6. The mask manufacturing method according toclaim 1, wherein the calculating an irradiating amount of radiationincludes calculating the irradiating amount of the radiation accordingto positional-deviation correction information indicating a relationshipbetween an irradiating position of the radiation in a thicknessdirection of the mask substrate and a change of a pattern position afterthe radiation is irradiated.
 7. The mask manufacturing method accordingto claim 6, wherein the irradiating position of the radiation is near acenter in the thickness direction of the mask substrate.
 8. The maskmanufacturing method according to claim 6, wherein the irradiatingposition of the radiation is nearer to a front surface in the thicknessdirection of the mask substrate than the center.
 9. The maskmanufacturing method according to claim 6, wherein the irradiatingposition of the radiation is nearer to a back surface in the thicknessdirection of the mask substrate than the center.
 10. The maskmanufacturing method according to claim 1, wherein the positionaldeviation information is information in which a positional deviationamount, obtained by subtracting a distance between designed positions oftwo patterns on the mask from a distance between two patterns actuallyformed on the mask that correspond to the two patterns, is associatedwith the actually formed pattern position, and only when the positionaldeviation amount is negative, the heterogeneous layer is formed.
 11. Themask manufacturing method according to claim 1, wherein the radiation isa laser beam or an ion beam.
 12. The mask manufacturing method accordingto claim 1, further comprising, after the forming an heterogeneouslayer, pressing a plurality of end surfaces of the mask substratesimultaneously to downsize the pattern formed on the mask substrate intoa predetermined size.
 13. The mask manufacturing method according toclaim 1, wherein the pattern is a reference pattern formed on the masksubstrate for detecting a positional deviation or a device pattern of asemiconductor device.
 14. The mask manufacturing method according toclaim 1, wherein the mask is an imprint mask.
 15. A semiconductor devicemanufacturing method comprising: coating an entire surface on aprocessing target film formed on a semiconductor substrate with acoating material; positioning the mask manufactured by the methodaccording to claim 14 with respect to the semiconductor substrate to bepressed on the processing target film via the coating material;solidifying the coating material; and separating the mask from theprocessing target film to process the processing target film by using acoating material pattern left on the processing target film as a mask.